The present invention relates to a claw pole generators.
Claw pole generators are known in the art. One of such generators is disclosed for example in the German patent 1 209 651. In this reference a claw pole generator has a drive shaft on which an excitation winding is arranged. A pole wheel half is mounted on the drive shaft at each longitudinal side of the excitation winding. Each pole wheel half includes a pole wheel disk also indicated as a plate, and a claw-shaped magnet pole which extends from an edge region of said plate in a longitudinal direction parallel to the drive shaft and identified as a claw. The both pole wheel halves are arranged so that the claws of one pole wheel half engage in the intermediate spaces formed between two neighboring claws of the other pole wheel halves. They surround the excitation winding.
An immovable stator is provided at a small radial distance from the claw. It is composed of metal plates which are provided with grooves and insulating from one another and which are assembled to form a plate pack. Windings of the stator winding are imbedded in the grooves. The axial length of the plate pack is identified as a so-called iron length and corresponds in the known generators substantially to the length of the claws.
The power characteristics of a claw pole generator depend on the iron length of the plate pack. In order to increase the power or reduce claw pole generators with maintaining the same power, research has been conducted to increase the iron length. However, the magnetic dissipation flux occurring between the neighboring claws increases and affects the desired power increase.
The negative action of the increasing dissipation flux can be reduced by the use of so-called permanent magnets in the region between two neighboring claws as proposed in the patent 1 209 651. However, the problem remains that the claw tips in the case of excessive length depending on high centrifugal forces expand radially outwardly and in the worse case collide with the plate pack of the stator.